Watch-crystal.



F. WEHINGER.

WATCH CRYSTAL.

APPLICATION nun SEPT. 22. 1916.

1,216,636. Patented Feb. 20,1917.

UNITED STATES PATENT oEEIcE.

FREDERICK WEHINGEB, OF WATERBURY, CONNECTICUT, ASSIGNOR TO WATERBUBYCLOCK CO., OF WATERBURY, CONNECTICUT, A CORPORATION.

WATCH-CRYSTAL.

Specification of Letters Patent.

Application filed September 22, 1916. Serial No. 121,575.

To all whom it may concern:

Be it known that I, FREDERICK WEH- INGER, a citizen of the UnitedStates, residing at Waterbury, in the county of New Haven and State ofConnecticut, have invented a new and useful Improvement inWatch-Crystals; and I do hereby declare the following, when taken inconnection with the accompanying drawings and the characters ofreference marked thereon, to be a full, clear, and exact description ofthe same, and which said drawings constitute part of this application,and represent, in

Figure 1 an edge view of an initially fiat, unbreakable watch-crystalformed in its edge with a circumferential retaining-groove.

Fig. 2 a plan view showing the crystal inserted into a bezel.

Fig. 3 a view thereof in transverse section.v

Fig. 4 a broken detail sectional view on an enlarged scale through theedge of the crystal.

. Fig. 5 an edge view of an initially concavo-convex watch-crystalformed in accordance with my invention.

Fig. 6 a broken detail sectional view thereof on an enlarged scalethrough its edge thereof.

My invention relates to an improvement in watch-crystals and isparticularly applicable to. unbreakable crystals of celluloid, or

kindred material, but also comprehends watch-or stals of glass, theobject of my invention being to produce av cheap watchcrystal ofsuperior appearance, to secure permanence of its retention in placeunder 4 all conditions of use, to compensate for variations of size andshape, and to reduce the cost of insertion.

With these ends in view, my invention consists in a watch-crystal havinga circumferential retaining-groove formed in its edge.

My invention further consists in a nonbreakable watch-crystal having acircumferential retaining-groove formedin its edge.

My invention further consists in a watchcrystal having a circumferentialretaininggroove formed in its edge in combination with a bezel formedwith a crystal-retaining edge and adapted to be sprung for the insertionof its retaining-edge into the groove of the crystal.

In carrying out my invention as shown in Figs. 1 to 4 inclusive, aninitially flat nonbreakable crystal 2 ofcelluloid, or kindredtransparent substance, is formed with a circumferential retaining-groove3 in its edge for the reception. of a crystal-retaining edge 4 formed ina bezel '5 which may be of any approved construction, provided only thatits said edge 4 is adapted to enter the groove 3 in the crystal 2.Preferably the crystal 2, prior to its insertion into the bezel 5, willbe strained into concavo-convex form as shown in Figs. 2 and 3 and soheld while the bezel 5 is sprung open by downward pressure upon itsouter edge 6 sufliciently to stretch and so enlarge its saidcrystal-retaining edge ,4 enough to permit the same to enter the groove3 of the crystal, or, without resorting to springing the bezel assuggested above, the crystal may be strained and concavo-convexed tosuch an extent as to sufliciently reduce it in diameter to permit it tobe set down into the bezel, the crystal being then allowed to expandunder its tension for the seating of its groove" 3 over the edge 4,after the same are brought into registration. In either case the crystalwill be maintained under stress, by the bezel, 1n concavo-convex sumeits flat initial form will assist' its groove in holding it in place. Orthe crystal might initially be made in concavo-convex form, orpermanently set in such form, in which case it would be held in placeentirely by the entrance into its circumferential groove of thecrystal-retaining edge of the bezel.

As shown in Fig. 5, the circumferential retaining-groove '3 is V-shaped,located exactly in the center of the edge of the crystal and flanked oneither side'by corresponding bevels 10, whereby a great economy of timeis secured in the insertion of the crystals into their bezels, since theoperator does not have to discriminate between the two faces of thecrystal as has heretofore been neces- Patented Feb. 20, 1917.

beveled retaining-edges in the plane of their inner faces. Practicallythe entire edges of crystals so made and held are exposed outside oftheir bezels, producing a thick and clumsy effect, even when glasscrystals of great purity are employed. This effect of thickness is, ofcourse, heightened when crystals of celluloid or kindred material areused, since the edges of such crystals are somewhat opaque and grayishin appearance.

Moreover, the edge of my improved watchcrystal is necessarily made sothick in order to provide room for its circumferential retaining-groove,that the danger of splintering it in inserting the crystal into thebezel, is negligible,whereas one of the greatest sources of expense andtrouble in the use of glass crystals as heretofore made, is that theirexcessively thin edges splinter when sprung into the rabbets formed fortheir reception in the bezels heretofore used. Furthermore, I am able,owing to the thickness of the edge of the crystal, to form theretaining-groove with a far higher degree of accuracy than it ispossible to grind a thin edge. The grinding of the retaining-edges ofglass-watch-crystals is largely a manual operation and subject to minuteand uncontrollablevariations due, in particular, to

' the fact that the crystals themselves being ini- 'tially slightlyconcavo-convex, vary enough in such shape to prevent the grinding oftheir edges with a high degree of accuracy.

In Figs. 5 and 6 I have shown "my invention as applied to awatch-crystal made of glass, the concavo-convex crystal 11 being formedin the center of its edge with a V- shaped groove 12 flanked by bevels13 and 14. This crystal is not only reversible face for face, but hasall of the advantages of permanence of retention in the bezel due to itsrelatively deep circumferential retaininggroove 13 for the reception ofthe crystalretaining edge 4 of the bezel which, in case of the use of aglass crystal, would have to be sprung for the reception of the crystalby pressure upon its outer edge.

I do not limit myself to a watch-crystal made of any one material, or toinserting it into its bezel in any particular way, my invention broadlycomprehending the formation of the edge of a watch-crystal with acircumferential retaining-groove for the reception of acrystal-retaining edge forming a feature of the bezel.=

I claim 1. A watch-crystal having a circumferential retaining-grooveformed in the center of its edge.

2. A non-breakable watch crystal having aeircumferentialretaining-groove formed in the center of its edge and flanked on eitherside by bevels.

In testimony whereof, I have signed this specification in the presenceof two subscribing witnesses.

FREDERICK WEHINGER.

Witnesses:

J. R. PUTNAM, Earn M. BARNUM.

